High-frequency translating circuits



Dec. 19, 1922. 4

' L. ESPENSCHIED ET AL.

HIGH FREQUENCY TBANSLATING CIRCUITS.

ORIGINAL FILED SEPT-30. 1919- 255 331;; Wei/v61 Patents Dec. 19, 1922.

STATES r at a" M LLOYD ESPENSCHIED, 0F QUEENS, AND HERMAN A. AFFEII, 0F BROOKLYN, YORK,

ASSIGNORS T0 AMERICAN TELEPHONE AND TELEGRAPH COMPANY, A CORPORA- rron or NEW YORK.

Original application filed September 30, 1919, Serial No. 327,399. Divided and this 18, 1921. Serial No. 470,585.

To all whom 1' If many concern:

Be it known that we. Lnorn EsrnNsomnn and Huron-m A. Arron, residing at Queens and Brooklyn. in the counties of (Queens and Kings. and State of New York, respectively,

filed September 30, 1919, entitled High frequency translating circuits.

As is well known, modulation of a plurality of frequencies consists in the superposition of the input currents upon each other, either in the modulator element, or at some point in the input side of the said element. By the term modulator element is meant any portion of an electrical circuit. the electrical constants of which may be varied in accordance with signal variations; thus, it may be a vacuum tube in which the output resistance is varied in accordance with grid potential, or an electric arc, the resistance of which is a function of the impressed voltage, or, it may be a reactance element such as an inductance, the effective permeability of which is varied-by a controlling circuit, or a condenser, the capacity of which may be controlled by variation in the plate separation or in the dielectrio constant.

It is desirable, therefore, to provide means for superposing the two input currents so as to avoid loss of energy and diminution of modulating efficiency arising from mutual shunting effects. There are, in general, two ways whereby the input currents may be superposed so as to be rendered mutually noninterfering,'one known as the method of balance and the other as the method of frequency selection. It is the object of this "invention: to show means for superposing the input circuits upon each other by the method of frequency selection, and also to show means which combine the method of frequency selection with the method of balance.

The invention disclosed in this applica- HIGH-FREQUENCY TRANSLATING CIRCUITS.

application filed May tion comprises an arrangement for the modulation of a plurality of frequencies by means of an are or a plurality of arcs, in which arrangement the input circuits are rendered mutually non-interfering either by means of the principle of selectivity alone or by the combination of the principles of selectivity and of balance.

This invention will be better understood from the following description read in connection with the attached drawing-of which Figure 1 shows the application of the prin-' ciple of selectivity and Figure 2 shows the combination of the principles of selectivity and of balance to prevent interference.

Figure 1 shows the application of this invention to a circuit in which an arc constitutes the modulator element. A represents an are between the electrodes 1 and 1', across which a direct current from the battery B is applied through the reactance coils C, and C Oscillations are set up in the output circuit 2 which embraces the antenna X. Low frequency signalling current in the transmitter T may be impressed upon the circuit 3 which is bridged across the electrodes 1 and 1-. A filter F is inserted in the low frequency circuit 3 adapted to transmit the low frequency signals of, for example, 10 to 2500 cycles, and will prevent the transmission therethrough' of frequencies below 10 and above 2500 cycles. High frequency oscillations will be set up in the circuit 2 in a manner that is well known, and these high frequency oscillations may ,be modulated by the low frequency current impressed upon the circuit 3 by the transformer T These low frequency signals will pass through the filter to the modulator device, namely the arc, but high frequency oscillations of the circuit 2 may not be transmitted through the filter F into the low frequency signaling circuit. This-circuit arrangement shows the means whereby the low frequency input circuit may be protected from interference by the high frequency oscillations of the oscillating circuit, which the low frequencies are adapted to modulate.

Figure 2 shows an arrangement for a balanced arc modulating system, in which the method of frequency selection is also applied in order to assure a higher degree of -tance L and the capacity protection of the frequencies in one input circuit from interference by currents in the other input circuits of the modulating de vice. In the circuit arrangement A and A; represent two arcs, which may be of any Well-known type, connected with a common source of direct current B and having .re-

actance coils C and C associated in the direct current circuit. The output circuit is represented by the antenna X, which has connected therein one of the windings 3 of the triple-winding transformer T The other two windings of the said transformer are connected in series with the arcs, each winding being individual to an arc circuit. These windings of the transformer are so arranged and designed that equal currents in the same direction in each arc conductor will cause no resultant action in the winding 3 which is connected with the antenna X. Under these conditions, the action of,

the two. arcs in parallel is equivalent to that of a single are connected across the source of direct current B and its fre uency of oscillation will be determined b t e induc- K Bridged across the arc conductors is alow frequency circuit 4 upon which signaling currents from thetransmitter T may be impressed. Inserted in the low frequency circuit is a filter F or its equivalent, which is adapted to transmit frequencies within the'range of 10 to 2500 cycles. Inserted in the two are conductors, between the point where the low frequency signaling circuit is connected across the two arcconductorsand thepoint of connection of the two are conductors with one side of the battery and the oscillation circuit, is a suppression filter F which is adapted to suppress oscillations havin a frequency between 10 and 2500 cycles an 'to transmit frequencies below 10 and above 2500 cycles.

Having in mind the foregoing description, the invention will be made clear from. the following description of its mode of operation:

Direct current will flow from the battery 13 through each of the arcs A and A and through the windings 1 and 2, which are respectively connected with the arcs A and A High fre uency, oscillations resulting in a manner t at is well known will be set up in the high frequency oscillating circuit which embraces the inductance L the capacity K and the parallel conducting paths containing the arc A the coil 1 and the arc A and the coil 2 respectively.

These oscillations will pass through thefilter F since it is designed to transmit high frequency oscillations. Since these currents are in the same direction in each of the" coils 1 and 2,-and of the same magnitude, no oscillations will be setup output circuit X. If, however, w frein the quency signaling currents are impressed across the arc conductors by means of the .view of the presence of the'filter F which suppresses frequencies between 10 and 2500 cycles, the low frequency current applied across the arc conductors will not be short circuited through the junction of the two are conductors with one side of the direct current circuit and the oscillating circuit.

'Furthermore, it will be seen that-the filter 1F, which is the type adapted to transmit frequencies between 10 and 2500 cycles will prevent high frequency oscillations from being impressed upon the low frequency transmitting circuit. This circuit shows means whereby-each input circuit of a balanced arc modulator may be protected from interference by frequencies which are foreign to that circuit.

Althou h this invention has been shown as embodled in particular forms and organizations of parts, it is to be understood that it is not limited to such forms and organizations, but may be embodied in other and different forms within the scope .of the appended claims.

What is claimed is:

1. In a signaling system, the combination of an oscillating arc circuit, an input circuit adapted to modulate the oscillations of the said arc circuit, and frequency selecting means associated with said input circuit toexclude therefrom oscillations of frequencies forei to it.

2. n a signaling system, the combination of a, balanced arc circuit comprising two arcs in parallel, and having a common oscillating circuit, an output circuit connected with each of said are circuits by balanced inductive means, whereby equal currents in the same direction in each of said are circuits will produce no effect in said output circuit, a

source of low frequency signals bridged across said are circuits for modulating the high frequency oscillations, and frequency selecting means connected with the arc circuits and with the low frequency signaling circuit, whereby each of said circuits is rendered free from interference byfrequenoies foreign to it.

3. In a high frequency signaling system, the combination of an antenna of an oscillatory arc circuit, a low frequency input circuit characterized by a source of low frequency variations and a filter adapted to transmit the said variations, but not the oscillations set up by the said arc.

cillation circuit so connected as to normally suppress the radiation of oscillations and a low frequency input circuit connected with the said oscillation circuit and having a filter associated therewith so arranged as toprevent high frequency oscillations from entering the said low frequency circuit.

5. In a high frequency signaling system, the combination of an antenna of a source of high frequency oscillations so connected With the said antenna that radiation is normally pressed, at source of low frequency variations connected across the said multiple connection of the said arcs and having frequency selecting means to transmit the low frequency variations and suppress the high frequenc oscillations.

7. n a high frequency signaling system, the combination-of a plurality of arcs, a high pass filter connected with the multiple conductors of the said arcs to prevent the short-circuiting of the low frequency variations by the multiple connection of the said arcs, and a low pass filter in the low frequency input circuit to suppress high frequency oscillations therein.

In testimony whereof, I have si ed my name to this specification this 13th day of May, 1921.

LLOYD ESPENSCHIED. In testimony whereof, I have signed my name to this specification this 16th day of May, 1921..

HERMAN A. AFFEL. 

